As mobile communications technologies develop rapidly, mobile data service traffic also increases sharply. To resolve a problem that the mobile data service traffic increases sharply, operators propose use of a small cell for offloading, that is, in a location with a relatively large quantity of mobile users, small cells with a relatively small coverage area are intensively deployed, so as to support enormous services generated in this area. An access node of the small cell is referred to as a small node, where the small node may be a low power node (LPN, Low Power Node), a femtocell (Femto), a low mobility cell (LoMo), a pico cell (pico), or the like.
The small node is generally deployed in an edge area of a macro base station. When user equipment (UE, User Equipment) is located in an area covered synchronously by the macro base station and the small node, an offloading transmission scheme may be used, that is, control plane signaling of the UE is transmitted in a source eNB (eNB, evolved Node B), and user plane data is transmitted in the small node. To perform a cell handover, the source eNB selects a target eNB for the UE according to a measurement result of the UE and radio resource management (RRM, Radio Resource Management) information. To ensure continuity and lossless transmission of a service, the source eNB switches a control plane and a user plane of the UE to those of the target eNB, and meanwhile, the LPN forwards, to the target eNB, user plane data of the UE buffered in a buffer.
However, because data stored in a buffer of the small node greatly increases user plane data is offloaded to the small cell, when the cell handover is being performed, a current serving small node needs to forward the data to the target eNB; therefore, a transmission resource required for transmission also increases, and a delay is relatively great.